The present invention relates to gate latches which can be used for securing in a closed position a gate, door or like structure. More particularly, the invention is concerned with a latch having a latching tongue which is urged to a latching position in which it engages and restrains a latch pin, the tongue being displaceable against the urging force to release the latch pin so that a gate or door may be opened. Usually such a latch is of an automatic closing type whereby when the gate or door is closed, the associated pin strikes the tongue and displaces it against the urging force to permit the pin to be received and then engaged.
Generally, the urging force is provided solely by gravity since such an arrangement is reliable and effective and in the case of automatic closing latches, minimises the force needed to strike and displace the tongue whereby the pin is received and retained by the tongue. However, in the context of the present invention, it is not only pure gravity latches to which the invention may be applied but also similar latches which may include an element of biasing e.g. through a spring.
The form of the most common long-standing gravity latch is one often known as a D-latch, whereby a D-shaped tongue is pivotally mounted in an edge region so as normally to fall down with a straight face approximately vertical and behind which a striker pin of the latch assembly engages in a latching position. Automatic latching is provided for by the curved leading face of the latch being adapted to be engaged so as to displace the latch tongue. However, such devices are relatively crude and do not provide any integrated locking function and are not adapted to be actuated from either side of a door or gate.
An important development in the art is that disclosed in the present applicant""s prior patent application 78822/98 (now 725095) filed in Australia and the subject of equivalent U.S. Pat. No. 6,058,747. That application disclosed a gravity latch having a housing incorporating a lock accessible to the front of a slim housing for the lock and optionally provided for a remote actuator to permit opening of the latch, providing it is unlocked, from the other side of the gate or door.
However, hitherto there has been available no more sophisticated gravity latch to the best of the applicant""s knowledge and with a view to devising improved functionality and more advantageous designs, the present applicant now provides a development which offers advances in the art.
According to the present invention there is, broadly, provided a latch for gates and doors and having front and rear units adapted to be mounted on opposite sides of a structure associated with a gate or door,
(i) the front unit having (a) a housing adapted to be mounted on the structure, (b) a manually displaceable latching tongue displaceably mounted in the housing and adapted to interengage with a striker pin mounted on a gate or door and for holding the striker pin in a closed position to prevent opening of the gate or door, (c) a locking element displaceably mounted in the housing for locking the tongue when in a locking position and displaceable to a retracted position in which the tongue is released, and (d) a key-activated front lock adapted to displace the locking element,
(ii) the rear unit having (a) a housing accommodating a key-actuated rear lock and (b) a displaceable element for displacing the latching tongue and,
the latch having connection means (a) operable on actuation of either the front lock or the rear lock to displace the locking element between its locking and retracted positions and (b) operable when either of the locks is in an unlocked position to permit a displaceable element of the rear unit to act through part of the connection means to displace the tongue to release the striker pin.
Preferably a rotary action is provided for displacement of the locking element through a lost motion system which permits the displacement of the latching system by either of the locks.
In a preferred embodiment, each lock can be of a quality cylinder-type with a rotatable lost-motion collar attached to the rear of the lock cylinder, the collar having an interior cavity with a cut-out typically of 270xc2x0, leaving a 90xc2x0 wedge such that there is engagement with a first flat bar forming part of the connection means, a portion of the relative rotation between the bar and the collar being free motion which can be taken up and further relative motion causes the collar and bar to move together. A suitable configuration at the respective front and rear locks is provided so that 90xc2x0 of rotation at either lock provides for lost motion effect whereby the locks can be independently locked and unlocked and thereby independently lock and unlock the locking element which is associated with and displaced by the first flat bar.
Preferably, rotational motion through interconnected gears is provided for rotating the locking element into position to engage the tongue.
In a preferred embodiment, the connection means includes an elongate strip-like connector which interconnects with the rear lock and is displaceable manually towards the front unit whereby a front portion of the connector engages the tongue and displaces it to release the striker pin, this action being possible when either of the locks are unlocked and the arrangement being such that locking of one of the locks displaces the locking element to lock the tongue and prevent the displacement of the tongue and the connector.
An advantageous design is one in which the rear and front locks are not axially aligned but offset and a gear box is used to transmit a rotary motion from the connector to the flat-bar which is axially offset and which extends forwardly to engage in a lost motion device associated with the front lock. Thus, in this embodiment, the flat bar directly displaces the locking element when rotation occurs. Rotation is applied directly from the front lock to the flat bar when lost motion has been taken up and further rotation occurs, and rotation is applied indirectly upon rotation of the connector when the rear lock is rotated and lost motion is taken up.
A significant aspect of the present invention is that it can be incorporated in a durable, secure and highly functional slimline housing adapted to be mounted on a gate post with access to the lock being through the surface of each housing remote from the gate post. Furthermore, at least in preferred embodiments, the connecting means can pass neatly through the gate post or other structure and preferably all that is needed is to bore a circular hole of the appropriate diameter in the appropriate location. This facilitates accurate and easy fitting without high trade skills or special equipment. No morticing is required for the structure.
Preferably, the rear unit housing incorporates a push button in which the rear lock is mounted, the push button being spring-biased to an outer position. The push button connects to the connecting means. Depression of the button is not possible when the locking element is engaged with the tongue by virtue of either lock being moved into the locked position.
Preferably, the front unit is formed with the tongue as a pure gravity latch which is mainly encased within a housing of the front unit.
The invention also extends to a front unit separately supplied and adapted to cooperate with a rear unit as described above and in any one of the forms described herein.